Postage payment systems have been developed employing postage meters, which are mass produced devices for printing a defined unit value for governmental (such as tax stamps, or postage stamp) or private carrier delivery of parcels and envelopes. These postage meter systems involve both pre-payment of postal charges by the mailer (prior to postage value imprinting) and post payment of postal charges by the mailer (subsequent to postage value imprinting). Postal charges (or other terms referring to postal) as used herein should be understood to mean charges for either postal charges, tax charges, or private carrier charges or the like (or postal service, tax service or private carrier service, as the case may be).
Some of the varied types of postage metering systems are shown, for example, in U.S. Pat. No. 3,978,457 for MICROCOMPUTERIZED ELECTRONIC POSTAGE METER SYSTEM, issued Aug. 31, 1976; U.S. Pat. No. 4,301,507 for ELECTRONIC POSTAGE METER HAVING PLURAL COMPUTING SYSTEMS, issued Nov. 17, 1981; and U.S. Pat. No. 4,579,054 for STAND ALONG ELECTRONIC MAILING MACHINE, issued Apr. 1, 1986. Moreover, other types of metering systems have been developed which involve different printing systems such as those employing thermal printers, ink jet printers, mechanical printers and other types of printing technologies. Examples of these other types of electronic postage meters are described in U.S. Pat. No. 4,168,533 for MICROCOMPUTER MINIATURE POSTAGE METER, issued Sep. 18, 1979 and, U.S. Pat. No. 4,493,252 for POSTAGE PRINTING APPARATUS HAVING A MOVABLE PRINT HEAD AND A PRINT DRUM, issued Jan. 15, 1985. These systems enable the postage meter to print variable information, which may be alphanumeric and graphic type information.
Postage metering systems have also been developed which employ encrypted information on a mailpiece. The postage value for a mailpiece may be encrypted together with other data to generate a digital token. A digital token is encrypted information that authenticates the information imprinted on a mailpiece such as postage value. Examples of postage metering systems which generate and employ digital tokens are described in U.S. Pat. No. 4,757,537 for SYSTEM FOR DETECTING UNACCOUNTED FOR PRINTING IN A VALUE PRINTING SYSTEM, issued Jul. 12, 1988; U.S. Pat. No. 4,831,555 for SECURE POSTAGE APPLYING SYSTEM, issued May 15, 1989; U.S. Pat. No. 4,775,246 for SYSTEM FOR DETECTING UNACCOUNTED FOR PRINTING IN A VALUE PRINTING SYSTEM, issued Oct. 4, 1988; U.S. Pat. No. 4,873,645 for SECURE POSTAGE DISPENSING SYSTEM, issued Oct. 10, 1989 and, U.S. Pat. No. 4,725,718 for POSTAGE AND MAILING INFORMATION APPLYING SYSTEMS, issued Feb. 16, 1988. These systems, which may utilize a device termed a Postage Evidencing Device (PED), employ an encryption algorithm which is utilized to encrypt selected information to generate the digital token. The encryption of the information provides security to prevent altering of the printed information in a manner such that any change in a postal revenue block is detectable by appropriate verification procedures.
Encryption systems have also been proposed where accounting for postage payment occurs at a time subsequent to the printing of postage. Systems of this type are disclosed in U.S. Pat. No. 4,796,193 for POSTAGE PAYMENT SYSTEM FOR ACCOUNTING FOR POSTAGE PAYMENT OCCURS AT A TIME SUBSEQUENT TO THE PRINTING OF THE POSTAGE AND EMPLOYING A VISUAL MARKING IMPRINTED ON THE MAILPIECE TO SHOW THAT ACCOUNTING HAS OCCURRED, issued Jan. 3, 1989; U.S. Pat. No. 5,293,319 for POSTAGE METERING SYSTEM, issued Mar. 8, 1994; and, U.S. Pat. No. 5,375,172, for POSTAGE PAYMENT SYSTEM EMPLOYING ENCRYPTION TECHNIQUES AND ACCOUNTING FOR POSTAGE PAYMENT AT A TIME SUBSEQUENT TO THE PRINTING OF POSTAGE, issued Dec. 20, 1994, or its Canadian counterpart patent No. 1 301 336.